This seems to be a large and sprawling project with a lot of JS includes (several of which have been commented out), as well as a large chunk of inline JS.This in turn makes it quite hard to debug, when a problem like this arises.

My advice would be to try and isolate the problem, by cutting out parts which are not relevant.For example, your problem is on the "Strassenlampe" page and has nothing to do with the map before it, so try and remove anything which is to do with the map (obviously just for trouble shooting purposes).

My initial suspicion would be that the JS file you think is responsible for this, is not actually being included.